The Iron Warrior

UW Team Competes in SAE Clean Snowmobile Challenge

On March 6, four members of the Clean Snowmobile Team headed out to compete in the SAE Clean Snowmobile Challenge. The challenge showcases snowmobiles that student teams from around the world have modified to reduce noise and emissions while maintaining performance. It consists of a number of events that evaluate those aspects of the snowmobile as well as the design process that created those results.

This year was the third year for our chassis engine combination. Given that, hopes were high leading up to competition; we knew what needed improvement from last year and had worked to improve in those areas (namely, leaking gas tanks). We also improved our muffler design in order to uninhibit exhaust flow and incorporate a new catalytic converter.

The first event of competition was a static and dynamic technical inspection of the sled. Having fixed the issue of the leaking gas tank and having kept many of the components the same from previous year, we expected to pass quickly. We did… almost. The judges requested that an modified clutch cover be added to our sled. It fell into a gray area of the rules but we quickly built the extra shielding requested with the help of the onsite machinist and were able to pass the inspection. Later in the week we discovered the “0.06 in thick 6061 Aluminum or equivalent” that was used was extra siding from the building that was home to the competition.

Next event: the 100 mile endurance ride. There were some concerns about the trail conditions, since spring was coming early in Northern Michigan. Chris Campbell had the questionably-enviable job of riding the snowmobile over the ice and slush for the event. Of the 13 snowmobiles at competition and 9 snowmobiles that started the ride, Waterloo was one of only 6 that finished.

After the strong performance in the endurance ride, and being joined by four more team members who drove up Tuesday night, we headed into the next events. On Wednesday our sled was tested for in-service emissions. The event took much longer than expected as there were difficulties getting the data acquisition equipment that is towed behind the snowmobile running. The freezing rain didn’t make it any easier for the event staff to fix the problems they were having. Waterloo had the 6th lowest tailpipe emissions in the event.

The other events on Wednesday were the oral design presentation and static display. These events are a chance to show the judges, other teams, and public the design work that goes into the snowmobiles. We were also joined by another four team members

One of the interesting systems that we presented was an electronic continuously variable transmission (eCVT) that Nick Mulder developed the control strategy for. An eCVT allows for the gear ratio to be controlled in such a way that the motor is always operating at it’s optimal load and speed. The eCVT was not used on the sled in competition for reliability concerns.

On Thursday, we had MSRP, noise, subjective handling, and the menacing lab emissions test. The MSRP consists of defending the suggested retail price for the sled with the modifications that have been made to it. The noise event measures the sound pressure at a set distance from a trail where the snowmobiles drive by at 35 mph. During subjective handling a number of volunteers and industry partners ride the snowmobiles around a test track and evaluate them on power, suspension, and rideability. Finally, the lab emissions involves the snowmobile being outfitted with emissions probes and run on a dyno test stand through a ramped modal test. This tests the total power and the emissions at 5 different speed and load points. The event is widely considered to be the most challenging of the competition.

We know why… After doing two power sweeps to verify the max power of our snowmobile, we began the ramped modal emissions test. The first mode is 2 minutes at full power. Just one minute in our engine suddenly lost torque. Seeing this, we shut down the test.

It was disappointing. We had been on track to a top five performance. We thought through our options and came to the conclusion: “We could swap the engine but we would do worse.” It felt like giving up, but by not competing in the rest of the events we would finish with more points.

The final events took place Saturday. The public is invited to watch as teams compete in cold start (“warm start” this year), acceleration (effectively a drag race), and objective handling (a time trial race through a narrow course of snow and, new for this year, mud holes).

On the whole, we enjoyed competition. We were 45 seconds from a top 5 finish. Our sled was running so reliably that we didn’t have to spend a single evening working on it. We even managed to go skiing one afternoon. We were able to learn a lot about the snowmobiling and auto industries.

During the weeks since competition, the team has had a chance to reflect on competition and make plans for our next snowmobile. We have decided that we will be switching to the electric (or zero emissions) class for next year. It’s a large change for us but we see it as a chance to include students from a broader range of departments (ECE, we’re looking at you) as well as provide more relevant learning experience.

We would like to thank everyone who helped us to compete this year, including the MME department, the Dean of Engineering, WEEF, Engsoc, Polaris Industries and the rest of our sponsors as well as our advisor Professor Teertstra. Check out sled.uwaterloo.ca or facebook.com/uwsled for more info!